Since June, Marco Rubio has (possibly) saved a Senate seat in Florida for Republicans, Evan Bayh has turned Indiana into a top-tier pickup for Democrats, and marquee candidates from both parties have unexpectedly stumbled.

It’s been that kind of summer in the fight for the Senate majority. A battleground map that once seemed set in place has instead seen a series of individual-state transformations, leaving both parties excited over newfound opportunities and worried over unforeseen liabilities.

No races have seen bigger shifts than the ones in Indiana and Florida, where the return of political stars Bayh and Rubio have turned each election on its head.

And in North Carolina, where Democrats struggled most of last year to even find a candidate, Republicans are worried the Democratic nominee’s surprisingly strong fundraising could threaten Sen. Richard M. Burr in a state that could turn blue in November.

Strategists from both parties caution that Strickland and Burr can still overcome their late-campaign challenges, but they add that neither is in the kind of shape most in their party expected when the year began. They also believe that for all the political star power that Bayh and Rubio bring, the veterans remain vulnerable at a time when voters are deeply dissatisfied with the status quo.

The changes have potentially rerouted the path back to a majority for Senate Democrats, who need to net at least four seats to win control of the legislative body if Hillary Clinton wins the presidency. Most Democratic and Republican strategists alike, in fact, now consider Indiana a better opportunity for Democrats than longstanding targets in New Hampshire and Pennsylvania.

Bayh faces Rep. Todd Young, a candidate well-liked by the GOP establishment but one who must quickly raise his name identification against a former senator who entered the race with a near $10 million war chest.

“Republicans had already put [Indiana] in their win column,” said Christie Roberts, political director from the Democratic Senatorial Campaign Committee, at a news conference in Philadelphia last week. “It immediately moves Indiana into one of our top pick-up opportunities.”

Three months before Election Day, in a battle thus far overshadowed by the presidential contest, both parties are confident the shifts work in their favor.

To Democrats, despite setbacks in Florida and Ohio, they have expanded the map of potential pickup chances while Republicans retreat from key battlegrounds. In Wisconsin, for example, an outside group affiliated with Charles and David Koch recently pulled TV advertising on behalf of Sen. Ron Johnson, a sign the group is skeptical the first-term incumbent could win. Polls show Johnson trailing former Sen. Russ Feingold.

In Colorado, GOP voters picked a nominee, local county commissioner Darryl Glenn, whose agenda and rhetoric could squander what Republicans once hoped was a rare opportunity this year to challenge a Democratic incumbent. Sen. Michael Bennet is now favored to retain his seat.

Democrats also remain confident that second-tier opportunities in Missouri and Arizona, seats held by Republican Sens. Roy Blunt and John McCain, could emerge late in the election as genuine chances for victory , especially if Trump’s campaign falters. Rep. Ann Kirkpatrick is on track to be the Democratic nominee in Arizona, a state that party strategists believe could shift left this year amid heavy, Trump-driven Latino turnout.

Missouri Secretary of State Jason Kander, meanwhile, has impressed Senate Democrats with his fundraising acumen and work ethic.

“If you just look at DSCC strategy the past few cycles, it’s always been to put races in play that nobody expects to put in play,” said Matt Miller, a Democratic strategist. “You don’t win all those, but you put enough of them in play, and you hope things happen.”

The party is especially high on North Carolina, however, where Democratic nominee Deborah Ross has raised more than the incumbent Burr in two successive fundraising cycles . Ross was far from the first pick of party leaders, who tried and failed to recruit former Sen. Kay Hagan and onetime Rep. Heath Shuler. But Ross has taken advantage of a liberal base in the state politically engaged by the controversy over state legislation banning transgender people from using their preferred choice of bathrooms.

“Nobody thought Burr was going to have real race,” Martha McKenna, a veteran Democratic strategist, said last week. “And Deborah Ross has done a great job.”

Republicans are no less confident about recent developments, saying that many of the core targets for Senate Democrats this year, in places like Ohio, have remained solidly in their column three months before the election.

That includes in Nevada, where Rep. Joe Heck takes on former state Attorney General Catherine Cortez Masto, a race where the National Republican Senatorial Committee this week began running a new pair of ads targeting the Democratic nominee .

“If the election were today, we’d hold the Senate, and nobody would have thought that six months ago,” said Rob Jesmer, a former executive director of the National Republican Senatorial Committee who has been bearish about Trump’s effect on the GOP down-ballot ticket.

In Ohio, Portman, running what many political operatives consider the best campaign of 2016, had $13.2 million on hand at the end of June, dwarfing Strickland’s $3.7 million. The GOP incumbent also received the endorsement of the Ohio Conference of Teamsters last week, an announcement that sent ripples of surprise through the state and Washington.

“Strickland is being dramatically outspent with no sign whatsoever of him being able to close that gap,” said one Democratic operative, who requested anonymity to speak candidly.

Democrats say they remain confident they can win Ohio, citing Portman’s former role as the U.S. Trade Representative at a time when support for free trade deals is politically toxic.

But they still have to face questions in Florida, where Rep. Patrick Murphy, if he defeats Rep. Alan Grayson in this month's Democratic primary, will now most likely take on Rubio.

“I think Rubio is going to be very, very hard to beat,” said another Democratic strategist involved in Senate races. “He’s just a better candidate than Patrick Murphy.”

The map hasn’t been completely turned upside down: Democrats still consider victories against Illinois Sen. Mark S. Kirk — who faces Rep. Tammy Duckworth — and Johnson as essential to their plans. And each party is still battling hard in New Hampshire and Pennsylvania, where recent polls have shown tight races.